1. Field of the Invention
The present invention relates to a two-wheel-drive/four-wheel-drive switching system for a vehicle.
2. Description of Background Art
Heretofore, a vehicle which can switch two wheel drive and four wheel drive is known.
FIGS. 7 to 9 show an example of the vehicle 1 that includes a body frame 3 with an engine 2 mounted in the center thereof. Front wheels 4 and rear wheels 5 are provided together with a steering handlebar 6 arranged in the front upper part of the body frame 3 for steering the front wheels 4. A fuel tank 7 is attached to the body frame 3 and a seat 8 is attached to the rear of the fuel tank 7.
Each front wheel 4 and each rear wheel 5 are supported by suspensions 9 and 10 provided to the body frame 3 as shown in FIG. 8 so that they can be vertically moved.
A final reduction gear unit 13 for the front wheels 4 and a final reduction gear unit 14 for the rear wheels 5, respectively, are coupled to the engine 2 via propeller shafts 11 and 12 provided to the body frame 3. The right and left front wheels 4 and the right and left rear wheels 5 are connected to the final reduction gear unit 13 for the front wheels 4 and the final reduction gear unit 14 for the rear wheels 5.
A two-wheel-drive/four-wheel drive switching system 15 for switching a state of rear wheel drive and a state of four wheel drive by connecting or disconnecting power transmitted to the front wheels 4 is provided between the final reduction gear unit for the front wheel 13 and the propeller shaft 11, for example.
Or the two-wheel-drive/four-wheel-drive switching system may be also provided between the rear propeller shaft 12 and the final reduction gear unit 14 for the rear wheels 5.
It is proposed to provide the structure shown in FIG. 9 for the two-wheel-drive/four-wheel-drive switching system.
The two-wheel-drive/four-wheel-drive switching system 15 illustrated in FIG. 9 is composed of a switching unit 17 for connecting or disconnecting a pinion shaft 16 of the final reduction gear unit for the front wheel 13 and the propeller shaft 11.
The switching unit 17 is installed in a casing 18 attached to the final reduction gear unit for the front wheel 13 and is provided with an inner ring 19 fitted to the pinion shaft 16 via a spline. An outer ring 21 surrounds the inner ring 19 and is supported by the casing 18 so that the outer ring can revolve. Plural connecting/disconnecting members 22 are inserted between the outer ring 21 and the inner ring 19 for connecting or disconnecting the outer ring 21 and the inner ring 19. A retainer 23 is provided for holding the connecting/disconnecting members 22 so that they can be inclined. An armature 24 is interlocked with the retainer 23 and a switching mechanism 25 is provided for inhibiting the movement of the retainer 23 by attracting the armature 24 to a rotor 26 coupled to the outer ring 21 by the magnetic force and connecting the outer ring 21 and the inner ring 19 via the connecting/disconnecting members 22 by inclining the connecting/disconnecting member 22.
The switching mechanism 25 is made of an electromagnet and is provided with an electromagnetic coil 27 provided inside the rotor 26 and is attached to the casing 18 via an outside flange 28 formed at one end of the electromagnetic coil 27.
The switching mechanism 25 is positioned by touching the outside flange 28 to a fitting section having a difference in a level 18a formed in the casing 18. The switching mechanism 27 is fixed to the casing 18 by fitting a circlip 29 inserted into a fitting groove 18b formed in a position apart from the fitting section 18a by a predetermined distance to the inside face of the casing 18.
The two-wheel-drive/four-wheel-drive switching system 15 configured as described above inhibits the revolution of the armature 24 and the retainer 23 by attracting the armature 24 by the magnetic force of the switching mechanism 25, constrains the movement of each connecting/disconnecting member 22, connects the inner ring 19 and the outer ring 21 via the plural connecting/disconnecting members 22 and hereby, turns a state of two wheel drive into a state of four wheel drive.
The revolution of the armature 24 is freed by disconnecting energizing to the switching mechanism 25, the transmission of power to the final reduction gear unit for the front wheel 13 is disconnected by returning the plural connecting/disconnecting members 22 to a neutral position by a return spring not shown and a state of four wheel drive is turned into a state of two wheel drive by only the rear wheels.
Such a conventional type two-wheel-drive/four-wheel-drive switching system 15 has the following problem to be improved.
The switching mechanism 25 is fixed to the casing 18 by holding the outside flange 28 between the fitting section 18a formed in the casing 18 and the circlip 29 fitted into the fitting groove 18b formed in the casing 18. However, a clearance may be made between the outside flange 28 and the circlip 29. The fitting section 18a depends upon the manufacturing quality of the thickness of the outside flange 28, that of the fitting groove 18b and further, that of the circlip 29.
As a result, it is considered that the switching mechanism 25 is moved in the axial direction of the casing 18 and an interval between the rotor 26 and the armature 24 may be varied.
The invention is made in view of the problem of such a conventional type. The object is to provide a two-wheel-drive/four-wheel-drive switching system for a vehicle wherein a switching mechanism 25 forming the two-wheel-drive/four-wheel-drive switching system is securely fixed and a function of the switching mechanism can be secured, preventing noise from being made.
A two-wheel-drive/four-wheel-drive switching system for a vehicle according to the present invention includes a switching unit provided to either of the power transmission mechanisms provided between an engine and a front wheel and between the engine and a rear wheel for connecting or disconnecting the transmission of power in the power transmission mechanism. A driving shaft couples to the drive side with a driven shaft fitted to the driving shaft via circular clearance. Plural connecting/disconnecting members are inserted into clearance between the driving shaft and the driven shaft for connecting or disconnecting the driving shaft and the driven shaft by fitting or drawing them to/apart from the opposite faces of the driving shaft and the driven shaft. A switching mechanism is provided for selectively locating the connecting/disconnecting members in a position where the driving shaft and the driven shaft are connected or in a position where they are disconnected. A casing is provided for housing the switching unit so as to achieve the object. The two-wheel-drive/four-wheel-drive switching system for the vehicle according to the present invention also includes an outside flange that is provided to an electromagnetic coil forming the switching mechanism. A fitting section having a difference in a level to which the outside flange is touched is formed with a fitting groove formed on the inside face at an interval equal to or larger than the thickness of the outside flange from the fitting section. A circlip is provided opposite to the outside flange and is inserted into the fitting groove. The outside flange is pressed on the fitting section by inserting a circular elastic member between the circlip and the outside flange.
A two-wheel-drive/four-wheel-drive switching system for the vehicle according to the present invention provides an elastic member that is formed by a wave washer.
A two-wheel-drive/four-wheel-drive switching system for the vehicle according to present invention provides an elastic member formed by a coned disc spring.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.